I have an iMac. Last night Apple had me erase my operating system and reinstall it. I have an external hard drive and did a back up just before we did that. Everything was there. Now that my computer is back up and running, I reinstalled Lightroom and am having trouble with the catalogs. Of course when I reinstalled Lightroom, it created a new catalog but I went back to my latest LIGHTROOM back up, double clicked and it seemed to pull up my previous catalog with some files missing. How do I recover those files? It's like they're there but. I'm attaching a screen shot.